Stabilizers for one-component diazotype materials



United States Patent M 3,102,812 STABILIZERS FOR ONE-COMPONENT DIAZOTYPE MATERIALS Walter J. Welch, Port Dickinson, N.Y., assignor to General Aniline & Film Corporation, New York, N.Y., a

corporation of Delaware No Drawing. Filed Nov. 16, 1960, Ser. No. 69,552

4 Claims. (CI. 96-75) The present invention relates to one-component diazotype materials and, in particular, to such materials containing a compound having the ability to stabilize and thus increase the shelf life of the diazotype material, and to insure the formation of clean backgrounds.

Light-sensitive diazotype materials are constituted by a base to which is im-bided a light-sensitive diazonium compound. Such materials are processed to dye images by exposure under a pattern and development with an alkali in the presence of an azo dye coupling component. In the areas which are exposed to light, the diazo compound is destroyed. In the unexposed areas, the diazo couples with the coupling component to produce the dye image. Diazotype materials are of two classes, to wit, oneand two-component types. The one-component type contains only the light-sensitive diazo compound and the two-component type contains both the diazo compound and a coupler. In the latter type, precoupling is prevented by the use of acids. In the one-component type, the sensitized material is brought into contact with the coupler in an alkaline solution.

In one-component type materials, shelf life may be a severe problem, despite the absence of couplers, due to deterioration of the light-sensitive diazonium compound which gives rise to colored decomposition products. To offset such tendency to deterioration, it has been proposed to use stabilizers; and, to this end, l,3,6-naphthalenetrisulfonic acid and its water-soluble salts are generally employed. While these materials are eifective stabilizers, they cause a yellowish background when used with certain diazos and increase background deterioration of printed materials.

It has now been discovered that these objections to the l,3,6-naphthalenetrisulfonic acid stabilizers can be overcome by replacing the same with naphthalene rnonoor disulfonic acids or their alkali metal salts, such as the sodium salt, potassium salt, lithium salt or the like. Not only do these monoand disulfonic acid compounds function as stabilizers, but they yield clean backgrounds and show vastly reduced print yellowing.

One-component diazotype materials containing such monoand disulfonic acid compounds as stabilizers constitute the purpose and object of the present invention.

The stabilizers contemplated herein are naphthalene monoor disulfonic acids or their alkali metal salts, particularly the sodium salts. The molecule of these compounds, excepting for the sulfonic acid group(s), should be unsubstituted. Examples of compounds which I have found to be particularly effective are:

2,7-naphthalenedisulfonic acid and its disodium salt 2,6-naphthalenedisulfonic acid and its disodium salt 1,5-naphthalenedisulfonic acid and its disodium salt Sodiu-m-l-naphthalenesulfonate and the free acid Sodium-Z-naphthalenesul-fonate and the free acid These compounds are known and, in fact, may be purchased on the open market.

The stabilizer may be applied to the base in the sensitizing solution or as a precoat component. In the latter 3,102,812 Patented Sept. 3, 1963 case, the base may be precoated with a solution of sodium caseinate and the stabilizer-aluminum silicate, a binder such as sodium caseinate, polyvinyl acetate or the like, and the stabilizer. Generally, the quantity of the stabilizer used will vary from about one to three parts of stabilizer to one part of diazonium compound.

The diazos which are employed are those usual in onecomponent diazotype materials and may be, for example, diazos from p-phenylene diamines in which one nitrogen atom is substituted by an alkyl, aryl or aralkyl group. Typically, I have used the diazo from p-(N-ethyl-N-benzyl) -aminoaniline; p-(N-diethyl -arnino-n-chloroaniline p- N-di-n-hexyl -aminoaniline; p- N-di-isoamyl -amino aniline; and the like. The diazos are employed in the form of double salts with zinc chloride, stannic chloride, or the like.

Similarly, the coupling components are of the type used in the one-component system and may be phloroglucinol, resorcinol, acetoacetanilide, or the like. Neither the diazos nor the couplers are critical to the invention.

The invention will be further illustrated by the following examples, although it is to be understood that the invention is not restricted thereto.

Example I A sensitizing solution is prepared as follows:

Water cc Citric acid g 0.5 Aluminum sulfate g 0.5 2,6-naphthalenedisulfonic acid g 2.0 4-N-ethyl-N-benzylaminobenzenediazonium chlorozincate g 1.5

This solution is applied to a starch sized direct process paper, dried and printed under a mercury vapor lamp. Development is obtained by applying the following alkaline solution:

G. Borax 40 Sodium carbonate 30 Thiourea 20 Phloroglucinol 8 Resorcinol 8 Sodium salt of isopropylnaphthalenesulfonic acid 2 Water to make 1000 cc.

Prints made from this sensitizing solution show a cleaner background and discolor less upon aging than a similar solution using l,3,6-naphthalenetrisulfonic acid. The shelf life of the 2,6-naphthalenedisulfonic acid material is as good as that using 1,3,6-naphthalenetrisulfonic acid.

When dried and printed under a mercury vapor lamp,

development is obtained with the following alkaline solution:

Borax 40 Sodium carbonate 30 Thiourea 20 Phloroglucinol 8 Resorcinol 8 Sodium salt of isopropylnaphthalenesulfonic acid 2 Water to make 1000 cc.

I specified, any of the rnonoor disulfonic acid compounds previously mentioned. I, therefore, do not intend to be limited in the patent granted except as necessitated by the appended claims.

I claim:

1. One-component, light-sensitive diazotype materials comprising a base having imbibed thereto a light-sensitive diazonium compound and as a stabilizer, a compound se- 4 lected from the class consisting of the monoand disulfonic acids of naphthalene and their alkali metal salts.

2. One-component, light-sensitive diazotype materials as defined in claim 1 wherein the stabilizer is used in an amount of from one to three parts to each part by weight of the diazoniu-m compound.

3. One-component, light-sensitive diazotype materials as defined in claim 1 wherein the stabilizer is the disodium salt of 2,6-naphthalenedisulfonic acid.

4. One-component, light-sensitive diazotype materials comprising a base precoated with a binder, a stabilizer selected from the class consisting of the monoand disulfonic acids of naphthalene and their alkali metal salts, said precoat having imbibed thereto a light-sensitive diazonium compound.

References Cited in the file of this patent UNITED STATES PATENTS 2,184,289 D angelmajer Dec. 26, 1939 2,529,029 Lantz et a1 'Nov. 7, 1950 2,655,448 Slifkin Oct. 13, 1953 2,780,547 Ferzola et al. Feb. 5, 1957 2,805,159 Unkauf Sept. 3, 1957 2,807,544 Frederick Sept. 24, 1957 2,807,545 Frederick Sept. 24, 1957 

1. ONE-COMPONENT, LIGHT-SENSITIVE DIAZOTYPE MATERIALS COMPRISING A BASE HAVING IMBIDED THERETO A LIGHT-SENSITIVE DIAZONIUM COMPOUND AND AS A STABILIZER, A COMPOUND SELECTED FROM THE CLASS CONSISTING OF THE MONO- AND DISULFONIC ACIDS OF NAPHTHALENE AND THEIR ALKALI METAL SALTS. 